1fxf

From Proteopedia

proteopedia linkproteopedia link

spinqualitylabelsall models 1fxf, resolution 1.85Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CARBOXYLIC ESTER HYDROLASE COMPLEX (DIMERIC PLA2 + MJ33 INHIBITOR + PHOSPHATE IONS)

Overview

We report the structures of the crystallographic dimer of porcine, pancreatic IB phospholipase A(2) (PLA2) with either five sulfate or, phosphate anions bound. In each structure, one molecule of a tetrahedral, mimic MJ33 [1-hexadecyl-3-(trifluoroethyl)-sn-glycero-2-phosphomethanol], and the five anions are shared between the two subunits of the dimer. The, sn-2-phosphate of MJ33 is bound in the active site of one subunit (A), and, the alkyl chain extends into the active site slot of the second subunit, (B) across the subunit-subunit interface. The two subunits are packed, together with a large hydrophobic and desolvated surface buried between, them along with the five anions that define a plane. The anions bind by, direct contact with two cationic residues (R6 and K10) per subunit and, through closer-range H-bonding interactions with other polarizable, ligands. These features of the "dimer" suggest that the binding of PLA2 to, the anionic groups at the anionic interface may be dominated by, coordination through H-bonding with only a partial charge compensation, needed. Remarkably, the plane defined by the contact surface is similar to, the i-face of the enzyme [Ramirez, F., and Jain, M. K. (1991) Proteins:, Struct., Funct., Genet. 9, 229-239], which has been proposed to make, contact with the substrate interface for the interfacial catalytic, turnover. Additionally, these structures not only offer a view of the, active PLA2 complexed to an anionic interface but also provide insight, into the environment of the tetrahedral intermediate in the rate-limiting, chemical step of the turnover cycle. Taken together, our results offer an, atomic-resolution structural view of the i-face interactions of the active, form of PLA2 associated to an anionic interface.

About this Structure

1FXF is a Single protein structure of sequence from Sus scrofa with CA, PO4 and MJI as ligands. Active as Phospholipase A(2), with EC number 3.1.1.4 Full crystallographic information is available from OCA.

Reference

Five coplanar anion binding sites on one face of phospholipase A2: relationship to interface binding., Pan YH, Epstein TM, Jain MK, Bahnson BJ, Biochemistry. 2001 Jan 23;40(3):609-17. PMID:11170377

Page seeded by OCA on Tue Nov 20 15:26:02 2007